In recent years, an electron microscope that is a type of a charged particle beam apparatus has been applied to a dimension measurement or defect inspection of a semiconductor device pattern. For example, for measurement of a gate dimension of a semiconductor device, a length measuring Critical-Dimension Scanning Electron Microscope (SEM) (hereinafter, referred to as CD-SEM) is used and for the defect inspection, a defect inspection SEM is used. Furthermore, a scanning electron microscope is used for conduction inspection of a wiring deep hole by using a potential contrast. Furthermore, there is also a focusing ion beam apparatus for processing and observing the semiconductor device by using an ion beam.
On the other hand, a surface of a sample such as a semiconductor wafer or the like that is an object to be measured or inspected by the charged particle beam apparatus described above may be covered by an insulation film. If the beam is applied to the sample, a surface potential of the sample is increased, which may cause focus shift or image drift. In order to suppress such an increase in the potential, an electrostatic chuck in which a contact pin is provided to break the insulation film of the surface of the sample is disclosed in PTL 1. Furthermore, in order to determine whether or not the contact pin and the sample are appropriately conductive, a method of evaluating a shift amount of a retarding voltage is described in PTL 1.